Copolymer compositions of benzalalkylimine



saturation.

United States 3,072,617 COPOLYMER COMPOITIONS F EENZAL- ALKYLKMLNE Ellis K. Fields, Chicago, Ill., assignor to Standard Oil Company, Chicago, Ill., acorjp oration of Indiana No Drawing. Filed Aug. 18, 19 58, Ser. No. 755,391 11 Claims, (l. 25078. 5)'

ing oils employed in internal combustion engines such as automotive and diesel engines require the use of one or more addition agents to improve their serviceability under certain adverse operating conditions. Among the more important additives employed is the type which functions to prevent the formation and accumulation of sludge and varnish-like coatings on pistons and cylinder walls of the engine. Such additives which have the property of maintaining clean engines are referred to as detergent-type addition agents. Other addition agents in common usage are known as viscosity index improvers. These additives function to improve the viscosity-temperature characteristics of the lubricant in which they are employed, said relationship commonly being expressed in the art as the viscosity index of the oil.

It is an object of this invention to provide n'd-vel copolymers of a benzalalkylimine such as benzalmethylimine. Another object of this invention is to provide novel addition agents which when added to a lubricant will improve both the detergent properties and the viscosity index thereof. Still another object is to provide lubricant comatent positions possessing improved detergency and viscositytemperature characteristics. Other objects and advantages of the invention will become apparent in the following description thereof.

The above objects, among others, are achieved in accordance with this invention by incorporating in a lubricatingoil a novel copolymer of benzalmethylimine with an ethylenically unsaturated monomer, said monomer being capable of addition homopolymerization through said un- My invention also provides new and useful copolymers of benzalalkylimine such as benzalmethylimineswith such homopolymerizable monomers in admixture with other monomers containing internal ethylenic unsaturation which do not readily homopolymerize. Benzalmethylimine (C H CH=NCI-I can readily be prepared by the reaction of benzaldehyde with methylar'nine, as is well known in the art. I have discovered that although a benzalalkylimine such as benzalmethylimine doesnot homopolymerize, it will copolymerize with other polymerizable monomers to form copolymeric products which are useful as detergent additives and viscosity index improvers in lubricating oils.

In' general, the monomers which willcopolymerize with benzalmethylimine in accordance with this invention are characterized by having ethylenic unsaturation, that is, they contain non-aromatic lgroup, i.e. a CH ==C group, wherein at least one of the.

fitice valence bonds is linked to a negative group, and the other bond is linked to hydrogen or hydrocarbongroups. The preferred monomers may therefore be defined as vinylidene compounds (which term is intended to include vinyl compounds) wherein there is attached to the vinylidene' group at least one negative group or radical such as an aryl group (for example, as in styrene, alphamethyl styrene, chlorinated styrenes, 3-methyl styrene, 3,4,5-trimethyl styrene, etc.); an acyloxy group (vinyl acetate; vinyl butyrate, vinyl decanoate, vinyl octadeca'noate, etc.) an alkoxy group (vinyl ethyl ether, vinyl butyl ether, vinyldecyl ether, vinyl ocetdecyl ether, etc.) an aroyloxy group (vinyl benzoate, vinyl toluate, etc); a carbalkoxy group (butyl acrylate, butyl methacrylate, octyl' acrylate, cetyl methacrylate,- laurylmethacrylate, octadecylacryla-te, octadecyl methacrylate, etc.); a halogen radical (vinyl chloride, vinyl bromide, vinyl iodide, vinyl fluoride, vinylidenechloride, etc.); a cyano group (acrylonitrile; methacryl onitrile, etc.); a lactam' group- (N-vinyl pyrr'olidone; N- vinyl piperidone, etc.). i

The reactive monomers, i.e., those capable" of forming homopolymers, can be used in admixture with other mono mers containing internal ethylenic unsatura'tion which donot readily homopolymerize but which will copolymerize with abenzalalkylimin'e such as benzalmethylimine and reaction monomer mixture. Thepreferred compounds of this type are esters of butenedio'ic acids having the general formula;

wherein R and R represent the sa'rnelor' different nryr radicals having from about 4 to about 22 carboiiat'oms, and preferably from about 6 to about 12 carbon a oms; and R is selected from the group consisting of hydrogen and a methyl'radica'l. Examples of such internally unsaturated compounds are dibutyl furnarat'e, di-iso-octylj furnarate, dilauryl fumarate, dioctadecyl fumarate and the corresponding esters of maleic, citra'conic and mesa-' co'nic acids.

The henz'alalkylirriines which may be usedforcop'o'lyiii erization with the admixture of reactive monomers" and monomers containing internal ethylenic maturation-- de fined above, are'the' benzalallylimin'es wherein th alkyl' group has-from 1 to 5 carbon atoms including methyl, ethyl, propyl, butyl and amyl groupsand their isomers.- The preferred" ben zalalkylimine is henz'alndethylirnihei For use as lubricating oil additives the copolymers of this invention must,'of course; be oil soluble. In order to achieve this endit is preferred that the polymer'izabl monomers used in conjunction withthe benzalalkylimirieeach have from about 6 to about 30 carbon atoms, ;andpreferably about 10 to about 24 carbon atoms in the mole-' cule; In any given case oil solu-bilitycan readilybe increased byadjusting the ratioof the reactants so as to incopolymer, for example the proportion of diisooctyl fum'arate in a' mixture ofthe same, styrene, and benzalmethylimine, or by increasing the chain lerigth'ofthe substituent hydrocarbon groups, for example, the es't'e'i group when an acrylate'orniethacrylate is usedor the side chain when" an alkyl st'yren'e" is used. Suitable mole ratios of benzalmethylimine to other monomers in the copolymer range from about '1 :200 to about 1: 1 and prefe'r'ahly from ture to obtain copolymers having a benzalmethylimine to other monomer ratio within the preferred range. It follows that the amount of vinylidene compound and internally unsaturated compound will be from 88 to 99 wt. percent of the total monomer mixture and preferably from 94 to 97 wt. percent. When a mixture of vinylidene compounds and internally unsaturated compounds (e.g., butenedioic acid esters such as maleates or fumarates) is used, the mole ratio of the vinylidene compounds to the internally unsaturated monomers should be at least as great as 1:1 in order to insure the formation of a copolymer.

The copolymerization can be carried out by any of the methods known to the art, i.e. in bulk. in solution or in emulsion. Bulk and solution polymerization are preferred, however. A particularly useful expedient is solution polymerization in which the solvent is a lubricating oil similar to that in which the additive is to be used, e.g., an SAE 10 to SAE 30 base oil when the additive is to be used in an automotive crankcase oil. This procedure results in a concentrate of the additive in oil solution which requires no purification and which is easily handled and dispensed.

In preparing the copolymeric products of this invention there can be employed as a catalyst any compound which is capable of initiating polymerization by providing stable free radicals under the conditions of the reaction. Examples of such catalysts are peroxy compounds, for example, organic peroxide, peroxy salts, hydroperoxides, etc., such as di-t-butyl peroxide, benzoyl peroxide, cumene hydro peroxide, t-butyl hydroperoxide, ethyl peroxy carbonate, and the like, and compounds such as a,u'-azodiisobutyronitrile. dimethyl and diethyl u,a-azodiisobutyrate, etc. Such initiators can be used in a concentration of about 0.1% to 1.0% by weight. In addition, polymerization may also be initiated by the use of ultraviolet light as well as by the use of heat alone.

In general. the range of polymerization reaction temperatures employed in producing the copolymers of the present invention varies between about 50 C. and 170 C. and is preferably within the range from about 100 C. to about 150 C. It will be understood that the polymerization temperature selected will usually be varied according to the nature and amount of the particular monomers and catalysts, if any, used, the desired polymerization temperature and the molecular weight of the products which are desired. Likewise the time for polymerization will be dependent on similar factors and can range over a period from about one hour to about 60 hours, as will be apparent to one skilled in the art. When the preferred operating temperature of about 100 to 150 C. is employed I have found that suitable copolymers can generally be produced within a period of about 8 to 40 hours, which is accordingly the preferred range of polymerization times.

The copolymerizations of the present invention can be effected at atmospheric or higher pressures. When a volatile comonomer is used, the process can be carried out under the autogenous pressure of the reaction mixture at the temperature employed. In most cases the preferred comonomers (for example, styrene, acrylates and methacrylates, and vinyl esters and others) are sufliciently nonvolatile at the preferred polymerization temperature of 100 to 150 C., that the use of pressures in excess of atmospheric pressure will not be necessary, although they can be used if desired.

For use as lubricant additives the copolymers of the invention should have molecular weights within the range from about 10,000 to about 125,000 and preferably within the range from about 20,000 to about 70,000. Such copolymers can be used in lubricating oils in concentrations of about 0.01% to about 10% by weight and preferably within the range from about 0.5% to about 4 EXAMPLE 1 A mixture of 30 ml. styrene, 65 ml. diisooctyl fumarate, 5 ml. benzalmethylimine and 0.2 ml. t-butyl hydroperoxide was heated at 118 C. for 40 hours. The resulting light red highly viscous copolymer did not have the sharp and penetrating odor of the benzalmethylimine. The copolymer was soluble in solvent extracted mineral oil and contained 0.34% nitrogen. Copolymer yield was 87 grams.

EXAMPLE 2 A mixture of 45 ml. lauryl methacrylate, 5 m1. benzalmethylimine, and 0.1 gram benzoyl peroxide was heated at C. for 24 hours. An orange red copolymer containing 0.194% nitrogen and completely soluble in solvent extracted mineral oil was formed. The copolymer yield was 38.6 grams and had no benzalmethylimine odor.

EXAMPLE 3 A mixture of 10 ml. N-vinyl pyrrolidone, 35 ml. diisooctyl fumarate, 5 ml. benzalmethylimine and 0.1 ml. t butyl hydroperoxide was heated at 125 C. for 40 hours. Forty-three point 4 (43.4) grams of red copolymer containing 2.67% nitrogen and soluble in solvent extracted mineral oil was formed from the monomer mixture.

EXAMPLE 4 EXAMPLE 5 A mixture of 23.1 ml. (0.2 mole) styrene, 45.2 grams (0.1 mole) dilauryl fumarate, 4.75 (0.05 mole) benzalmethylimine, and 0.1 ml. t-butyl hydroperoxide was heated at 120 C. for 16 hours and at C. for 4 hours. An orange copolymer soluble in solvent extracted mineral oil and containing 0.361% nitrogen was formed from the mixture. Yield of copolymer was 67.6 grams.

EXAMPLE 6 For comparison, and not according to the present invention, a mixture of 23.1 ml. (0.2 mole) styrene, 45.2 grams (0.1 mole) dilauryl fumarate, and 0.1 ml. t-butyl hydroperoxide was heated for 16 hours at 120 C. and for 4 hours at 140 C. Sixty-five (65) grams of a clear colorless copolymer soluble in solvent extracted mineral oil was formed.

EXAMPLE 7 Again for comparison with the benzalmethylimine copolymers, the procedure of Example 1 was used to form a copolymer of benzalethylimine with styrene and diisooctyl fumarate.

EXAMPLE 8 For comparison with the benzalmethylimine copolymers, a copolymer of benzalisopropylimine with styrene and diisooctyl fumarate was prepared by the procedure set out in Example 1.

EXAMPLE 9 Further for comparison with the benzalmethylimine copolymers, a copolymer of benzal t-butyl imine with styrene and diisooctyl fumarate was also prepared by the procedure of Example 1.

The polymeric products of Examples 1-6 were tested for their effectiveness as viscosity index improvers at a concentration of 2% by weight in a solvent extracted SAE 5 mineral oil base. The results are given in the following table.

The effectiveness of the copolymers of the present invention in improving the detergency characteristics of lubricating oils is demonstrated by the data in Table II. These data were obtained by subjecting a lubricant composition with and" without the products of Examples 1-6 to the detergency and oxidation test known as the Indiana Stirring Test (I.S.C.TL). In this test 250 cc. of the oil to be tested is heated at 330-332 F. in a 500 cc. glass beaker in the presence of sq. mm. of copper and sq. mm. of iron. Four glass rods of 6 mm. diameter are suspended in the oil' which is stirred at about 1300 r.pm. by means of aglass stirrer. At intervals of 24, 48 and 72 hours oil samples are withdrawn and sludge, acidity, and varnish values are determined. Varnish values or ratings are based upon visual inspection of the glass rods, in which a rod free of any varnish deposit is given a rating of 10 while a badly coated rod is given a rating of 1. Rods having appearances between these extremes are given intermediate values. The copolymers of this invention were tested at 2% by weight concentration in a solvent extracted SAE 30 mineral oil base con- 6 Table III Product: Percent settled in 1 20 hours None 90 (in 4 hours). Example 1 0. Example 2 0. Example 3 0. Example 4 0. Example 5 0. Example 6 100 (in 2 hours). Example 7 20. Example 8 30. Example 9 45.

It can be seen from the above data that the novel co polymers of my invention are effective both as viscosity index improvers and detergents in oils. By contrast, a

comparison in Table III of the product of Example 6 with that of Example 5 demonstrates thatpolymers similar to those of the invention except containing no benzal i'mine possess no detergent properties whatsoever. Comparison of the percents of carbon settled in the presence of, the copolymers of benzalethylimine, for benzalisopropylimine and of benzal t-butylimine of Examples 7 and 8 and 9 with percentage of carbon settled in the presence of the benzal methylimine copolymer of Example l, having the same copolymerized materials, demonstrates the detergency properties of all of the benzalalkylimine copolymers prepared as well as the remarktaining 0.75% of sulfurized dipentene, with the results ably complete detergency of the preferred benzalmethylimine copolymers.

The products of this invention can be used in lubrieating oils in concentrations of from about 0.01% to about 10% and preferably from about 0.5% to about 5% by weight. Although the present invention has been illustrated by the use of these products in mineral lubrieating oils it is not restricted thereto. Gther lubricating oil bases can be used, such as hydrocarbon oils, both shown in Table II. natural and synthetic, for example, those obtained by the Table II Varnish Rating N aphtha Insoluble Acidity (mg,.KOH

(Sludge) per g. 011) Additive .24 Hrs; 48 Hrs. 72 Hrs. 24 Hrs. 48'Hrs. 72 Hrs. .24'Hrs. 48 Hrs. 72 Hrs;

None 10 8 5 0. 071 2. 1 5. 7 3. 92 7. 0 10.08 Product of Example 1 10 10 10 trace trace 2. 7 2. 8 3. 3 4. 4 Product of Example 2 1O 10 10 trace 0. 4 4. 2 3. 3 3. 6 5. 6 Product of Example 3 10 10 9 trace 0.8 2. 4 2. 8 3. 3 3. 3 Product of Example 4 1O 10 9 trace 1. 2 4. 1 2. 8 3. 3 4. 4 Product of Example 5... 1O 10 10 trace 0.8 3. 1 4. 2 4. 2 5.6 Product of Example 6 10 9 7 trace 3. 0 5. 7 3. 4 4. 2 7. 7

1 Milligrams per 10 grams oil.

With reference to the above data of Table II it is seen that the polymers of my present invention in comparison with the mineral oil alone and the polymer of Example 6, having no benzalmethylimine content, gave superior results when tested for acidity, varnish deposits, and naphtha insoluble sludge formation in the detergency and oxidation test.

The detergent properties of the copolymers of my invention are further demonstrated by the comparative data in Table III, which are the results of the carbon suspension test (C. B. Biswell et al., Ind. Eng. Chem. 47, 1598, 1601 (1955). The products were tested at 0.5 concentration in 70 cc. kerosene with three grams of a paste containing 20% carbon black in a heavy white oil base, stirring the mixture five minutes in a 100 cc. graduate in a Herschel demulsibility tester at room temperature (25 C.). After 5 days (120 hours) the perpolymerization of olefins, as well as synthetic lubricating oils of the alkylene oxide type and the polycarboxylic acid ester type, such as the oil soluble esters of adipic acid, sebacic acid, azelaic acid, etc. It is also contemplated that various other well known additives, such as anti-oxidants, anti-foaming agents, pour point depressors, extreme pressure agents, antiwear agents, etc., may be incorporated in lubricating oils containing the additives of my invention.

. Addition agent concentrates of a suitable oil base containing more than 10%, for example up to 50% or more, of the copolymers of this invention alone or in combination with other additives can be used for blending with hydrocarbon oils or other oils in the proportions desired for the particular conditions of use to give a finished product containing from about 0.01% to about 10% of the copolymers of this invention.

Unless otherwise stated, the percentages given herein and in the claims are percentages by weight.

While I have described my invention by references to specific embodiments thereof, the same are given by way of illustration only. Modifications and variations will be apparent from my description to those skilled in the art.

I claim:

1. An oil soluble copolymer of at least one homopolymerizable monomer having terminal ethylenic unsaturation linked to a negative organic group and a benzalalkylimine wherein the alkyl group of the benzalalkylimine contains from 1 to carbon atoms.

2. As a new composition of matter, an oil soluble copolymer of benzalmethylimine and at least one ethylenically polymerizable unsaturated vinylidene compound having from 6 to 30 carbon atoms and having at least one valence bond of the vinylidene group linked to a negative organic group.

3. The composition of claim 2 wherein the ethylenically polymerizable unsaturated vinylidene compound is selected from the group consisting of styrene, N-vinyl pyrrolidone and lauryl methacrylate.

4. The composition of claim 3 wherein the ethylenically polymerizable unsaturated vinylidene compound is N-vinyl pyrrolidone.

5. An oil soluble copolymer of a homopolymerizable monomer containing from 6 to 30 carbon atoms and having terminal ethylenic unsaturation linked to a negative organic group, an ester of a butenedioic acid having internal ethylenic unsaturation, and containing from 6 to 30 carbon atoms and a benzalalkylimine wherein the alkyl group of the benzalalkylimine contains from 1 to 5 carbon atoms.

6. As a new composition of matter, an oil soluble copolymer of benzalmethylimine, at least one ethylenically polymerizable unsaturated vinylidene compound having at least one of the valence bonds of the vinylidene group linked to a negative organic group, and at least one diester of a butene dioic acid, said diester containing from 6 to 30 carbon atoms in the molecule and having the general formula:

0 E R3 0 H I I ll r -t OR; OR:

wherein R and R represent alkyl radicals having from 4 to 22 carbon atoms and R is selected from the group consisting of hydrogen and a methyl radical, the mole ratio of said vinylidene compound to said diester being at least as great as 1:1.

7. The composition of claim 6 wherein the ethylenically polymerizable unsaturated vinylidene compound is selected from the group consisting of styrene, N-vinyl pyrrolidone, and lauryl methacrylate.

8. The composition of claim 7 wherein the ethylenically polymerizable unsaturated vinylidene compound is a mixture of styrene and N-vinyl pyrrolidone and the diester is diisooctyl fumarate.

9. As a new composition of matter, an oil soluble copolymer of benzalmethylimine and ethylenically polymerizable unsaturated monomer comprising benzalmethylimine and ethylenically polymerizable unsaturated monomer having from 10 to 24 carbon atoms in a molar ratio in the range of from 1:200 to 1:1, said ethylenically polymerizable unsaturated monomer containing an ethylenically homopolymerizable unsaturated vinylidene compound containing from 10 to 24 carbon atoms and having the terminal polymerizable ethylenic group linked to a negative organic group, said vinylidene compound being present in a mole ratio of at least 1:2 based on total moles of the ethylenically polymerizable unsaturated monomer.

10. An oil soluble copolymer of styrene, diisooctylfumarate and a benzalalkylimine wherein the alkyl group of the benzalalkylimine contains from 1 to 5 carbon atoms.

11. An oil-soluble copolymer of at least one homopolymerizable monomer containing from 6 to 30 carbon atoms and having a terminal ethylenic group linked to a negative group and a benzalalkylimine wherein the alkyl group of the benzalalkylimine contains from one to 5 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,457,873 DAlelio Jan. 4, 1949 2,606,172 Tawney Aug. 5, 1952 2,653,133 Catlin Sept. 22, 1953 2,800,452 Bondi et al. July 23, 1957 2,836,580 Wesp et a1. May 27, 1958 OTHER REFERENCES Van Alphen: Recueil des tlravaux chimiques des Pays- Bas, vol. 61, pages 8957 (1942). 

1. AN OIL SOLUBLE COPOLYMER OF AT LEAST ONE HOMOPOLYMERIZABLE MONOMER HAVING TERMINAL ETHYLENIC UNSATURATION LINKED TO A NEGATIVE ORGANIC GROUP AND A BENZALAKYLIMINE WHEREIN THE ALKYL GROUP OF THE BENZALALKYLIMINE CONTAINS FROM 1 TO 5 CARBON ATOMS. 